isabelle/valid/mathd_numbertheory_405.thy (18 lines of code) (raw):

(* Authors: Albert Qiaochu Jiang *) theory mathd_numbertheory_405 imports Complex_Main begin theorem mathd_numbertheory_405: fixes a b c :: nat and t :: "nat \<Rightarrow> nat" assumes h0 : "t 0 = 0" and h1 : "t 1 = 1" and h2 : "\<And>n. (n > 1) \<Longrightarrow> t n = t (n-2) + t (n-1)" and h3 : "a mod 16 = 5" and h4 : "b mod 16 = 10" and h5 : "c mod 16 = 15" shows "(t a + t b + t c) mod 7 = 5" sorry end